Organo-fluorine compounds are widely used as chemotherapeutic agents. More recently 18F-labeled compounds have become important in positron emission tomography. Although a variety of fluorinating agents and fluorinating methods are known there are very few known ways of introducing fluorine into electron rich systems such as olefins, aromatics, etc. In fact the great majority of fluorinating agents are nucleophilic. Since fluorine is the most electronegative element known it is not surprising that few electrophilic fluorinating reagents are available. We propose, as part of a FIRCA grant, to prepare and investigate 10-electron isoelectronic Xe(II), Se(IV), Te(IV) and Bi(V) as "power variable electrophilic fluorinating agents". The proposed chemistry is analogous to the chemistry of Iodine (III) that is experiencing a Renaissance. Specifically, ArSeF3, ArTeF3 and Ar3BiF2 along with XeF2 will be investigated as fluorinating agents for olefins. Likewise FXeOSO2F, FXeOSO2CF3 and Xe(OSO2F)2, Xe(OSO2CF3)2 will be investigated as a means of electrophilic introduction of these fluorosulfonate groups into olefins. Biologically active compounds such as fluorosteroids will be prepared along with other medicinally useful fluorocompounds.